Interior cabins of vehicles typically include cabin vents or pressure relief devices. Without such devices, air pressure inside the vehicle cabin could damage occupants' ear drums. Further, when a vehicle door is closed, air pressure within the vehicle needs to be relieved or the door will not close. If an air bag is activated in a vehicle that does not have a venting or pressure relief device, an occupant's ear drums may be damaged.
Pressure relief devices are usually hidden from view. For example, a pressure relief device may be found in a trunk or on a body frame pillar structure. Each pressure relief device is adapted to allow air to pass out of an enclosed structure, while also preventing a significant amount of air, dust, water or other contaminants into the enclosed area. Thus, pressure relief devices are, in essence, one-way valves or one-way check valves, and are configured to maintain a small amount of back pressure per customer specifications.
A conventional pressure relief device includes a plastic housing having a plurality of air passages. A light membrane (for example, a flap) is positioned over the air passages, and is configured to allow air to pass in one direction. In order to allow air to pass, the light membrane opens off of the main body in response to air flow. Typically, a seal is provided around the main body and acts to seal the hole in the mating structure upon assembly. The seal is typically molded around the main body in a secondary molding operation, or may be adhesively or chemically attached to the main body.
During installation, the pressure relief device may be snap fit to a structure. Typically, a user presses on the four corners of the pressure relief device in order to secure it within a reciprocal hole in a structure, such as a frame or sheet within a vehicle.
Pressure relief valves are shown and described in, for example, EP 2050600, U.S. Pat. Nos. 5,105,849, 5,759,097, 5,727,999, 5,904,618, and EP 1985480.
Many known pressure relief valves generate noise when membrane flaps return to their at-rest positions within air passage chambers of housings. For example, as the membrane flaps move back to at-rest positions and abut into a rim or lip surrounding an air passage(s), the contact therebetween may generate undesirable noise. Typically, the rim or lip surrounding the air passage(s) is formed of a hard plastic, along with the rest of the housing. As such, when the membrane flap returns to a hard stop on the rim, a noticeable sound may be generated. In order to reduce such noise, some known pressure relief valves include felt flaps. However, such flaps may not provide desired response to exerted air pressure, as they may be heavier and/or less flexible than typical membrane flaps, for example.